In skeletal muscle advanced glycation end products (AGEs) inhibit insulin action and induce the formation of multimolecular complexes including the receptor for AGEs.
Chronic hyperglycemia promotes insulin resistance at least in part by increasing the formation of advanced glycation end products (AGEs). We have previously shown that in L6 myotubes human glycated albumin (HGA) induces insulin resistance by activating protein kinase Calpha (PKCalpha). Here we show that HGA-induced PKCalpha activation is mediated by Src. Coprecipitation experiments showed that Src interacts with both the receptor for AGE (RAGE) and PKCalpha in HGA-treated L6 cells. A direct interaction of PKCalpha with Src and insulin receptor substrate-1 (IRS-1) has also been detected. In addition, silencing of IRS-1 expression abolished HGA-induced RAGE-PKCalpha co-precipitation. AGEs were able to induce insulin resistance also in vivo, as insulin tolerance tests revealed a significant impairment of insulin sensitivity in C57/BL6 mice fed a high AGEs diet (HAD). In tibialis muscle of HAD-fed mice, insulin-induced glucose uptake and protein kinase B phosphorylation were reduced. This was paralleled by a 2.5-fold increase in PKCalpha activity. Similarly to in vitro observations, Src phosphorylation was increased in tibialis muscle of HAD-fed mice, and co-precipitation experiments showed that Src interacts with both RAGE and PKCalpha. These results indicate that AGEs impairment of insulin action in the muscle might be mediated by the formation of a multimolecular complex including RAGE/IRS-1/Src and PKCalpha.
Cassese
Angela
A
Dipartimento di Biologia e Patologia Cellulare e Molecolare and Istituto di Endocrinologia ed Oncologia Sperimentale del Consiglio Nazionale delle Ricerche, Università degli Studi di Napoli Federico II, Naples 80131, Italy.
Esposito
Iolanda
I
Fiory
Francesca
F
Barbagallo
Alessia P M
AP
Paturzo
Flora
F
Mirra
Paola
P
Ulianich
Luca
L
Giacco
Ferdinando
F
Iadicicco
Claudia
C
Lombardi
Angela
A
Oriente
Francesco
F
Van Obberghen
Emmanuel
E
Beguinot
Francesco
F
Formisano
Pietro
P
Miele
Claudia
C
D000818:Animals; D005260:Female; D005951:Glucose Tolerance Test; D017127:Glycation End Products, Advanced / Q000378:metabolism*; D006801:Humans; D006943:Hyperglycemia / Q000473:pathology; D007328:Insulin / Q000378:metabolism*; D055504:Insulin Receptor Substrate Proteins / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018482:Muscle, Skeletal / Q000378:metabolism; D051571:Protein Kinase C-alpha / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D000067759:Receptor for Advanced Glycation End Products; D011971:Receptors, Immunologic / Q000378:metabolism; D019061:src-Family Kinases / Q000378:metabolism
D017127:Glycation End Products, Advanced; D007328:Insulin; D055504:Insulin Receptor Substrate Proteins; C526295:Irs1 protein, mouse; D000067759:Receptor for Advanced Glycation End Products; D011971:Receptors, Immunologic; D019061:src-Family Kinases; D051057:Proto-Oncogene Proteins c-akt; D051571:Protein Kinase C-alpha